An apparatus for gas chromatographic analysis essentially consists of an injector, a gas-chromatographic column with stationary phase coating housed in a temperature-controlled oven, and a detector.
A liquid sample consisting of the substances to be analysed and a solvent therefore is introduced in the injector, this sample being directly injected in the gas chromatography column or in a pre-column generally without stationary phase, or in a vaporisation chamber which is independently heated or heatable, where the sample is vaporized before being introduced in the column via a carrier gas.
The current trend is to increase the sample volumes for being able to analyze trace components. However, this implies the formation of important volumes of vaporized solvent, which are normally eliminated before the same enters the gas chromatography column, either at the same injector or at the end of a pre-column.
Eliminating most of the solvent is required, though this entails the risk that the most volatile components of the material to be tested are lost by being entrained by the vaporized solvent.